using System;

namespace Org.BouncyCastle.Crypto.Digests
{
    /**
    * implementation of RipeMD128
    */
    public class RipeMD128Digest
		: GeneralDigest
    {
        private const int DigestLength = 16;

        private int H0, H1, H2, H3; // IV's

        private int[] X = new int[16];
        private int xOff;

        /**
        * Standard constructor
        */
        public RipeMD128Digest()
        {
            Reset();
        }

        /**
        * Copy constructor.  This will copy the state of the provided
        * message digest.
        */
        public RipeMD128Digest(RipeMD128Digest t) : base(t)
        {
            H0 = t.H0;
            H1 = t.H1;
            H2 = t.H2;
            H3 = t.H3;

            Array.Copy(t.X, 0, X, 0, t.X.Length);
            xOff = t.xOff;
        }

		public override string AlgorithmName
		{
			get { return "RIPEMD128"; }
		}

		public override int GetDigestSize()
		{
			return DigestLength;
		}

		internal override void ProcessWord(
            byte[] input,
            int inOff)
        {
            X[xOff++] = (input[inOff] & 0xff) | ((input[inOff + 1] & 0xff) << 8)
                | ((input[inOff + 2] & 0xff) << 16) | ((input[inOff + 3] & 0xff) << 24);

            if (xOff == 16)
            {
                ProcessBlock();
            }
        }

        internal override void ProcessLength(
            long bitLength)
        {
            if (xOff > 14)
            {
            ProcessBlock();
            }

            X[14] = (int)(bitLength & 0xffffffff);
            X[15] = (int)((ulong) bitLength >> 32);
        }

        private void UnpackWord(
            int word,
            byte[] outBytes,
            int outOff)
        {
            outBytes[outOff]     = (byte)word;
            outBytes[outOff + 1] = (byte)((uint) word >> 8);
            outBytes[outOff + 2] = (byte)((uint) word >> 16);
            outBytes[outOff + 3] = (byte)((uint) word >> 24);
        }

        public override int DoFinal(
            byte[] output,
            int outOff)
        {
            Finish();

            UnpackWord(H0, output, outOff);
            UnpackWord(H1, output, outOff + 4);
            UnpackWord(H2, output, outOff + 8);
            UnpackWord(H3, output, outOff + 12);

            Reset();

            return DigestLength;
        }

        /**
        * reset the chaining variables to the IV values.
        */
        public override void Reset()
        {
            base.Reset();

            H0 = unchecked((int) 0x67452301);
            H1 = unchecked((int) 0xefcdab89);
            H2 = unchecked((int) 0x98badcfe);
            H3 = unchecked((int) 0x10325476);

            xOff = 0;

            for (int i = 0; i != X.Length; i++)
            {
                X[i] = 0;
            }
        }

        /*
        * rotate int x left n bits.
        */
        private int RL(
            int x,
            int n)
        {
            return (x << n) | (int) ((uint) x >> (32 - n));
        }

        /*
        * f1,f2,f3,f4 are the basic RipeMD128 functions.
        */

        /*
        * F
        */
        private int F1(
            int x,
            int y,
            int z)
        {
            return x ^ y ^ z;
        }

        /*
        * G
        */
        private int F2(
            int x,
            int y,
            int z)
        {
            return (x & y) | (~x & z);
        }

        /*
        * H
        */
        private int F3(
            int x,
            int y,
            int z)
        {
            return (x | ~y) ^ z;
        }

        /*
        * I
        */
        private int F4(
            int x,
            int y,
            int z)
        {
            return (x & z) | (y & ~z);
        }

        private int F1(
            int a,
            int b,
            int c,
            int d,
            int x,
            int s)
        {
            return RL(a + F1(b, c, d) + x, s);
        }

        private int F2(
            int a,
            int b,
            int c,
            int d,
            int x,
            int s)
        {
            return RL(a + F2(b, c, d) + x + unchecked((int) 0x5a827999), s);
        }

        private int F3(
            int a,
            int b,
            int c,
            int d,
            int x,
            int s)
        {
            return RL(a + F3(b, c, d) + x + unchecked((int) 0x6ed9eba1), s);
        }

        private int F4(
            int a,
            int b,
            int c,
            int d,
            int x,
            int s)
        {
            return RL(a + F4(b, c, d) + x + unchecked((int) 0x8f1bbcdc), s);
        }

        private int FF1(
            int a,
            int b,
            int c,
            int d,
            int x,
            int s)
        {
            return RL(a + F1(b, c, d) + x, s);
        }

        private int FF2(
            int a,
            int b,
            int c,
            int d,
            int x,
            int s)
        {
        return RL(a + F2(b, c, d) + x + unchecked((int) 0x6d703ef3), s);
        }

        private int FF3(
            int a,
            int b,
            int c,
            int d,
            int x,
            int s)
        {
        return RL(a + F3(b, c, d) + x + unchecked((int) 0x5c4dd124), s);
        }

        private int FF4(
            int a,
            int b,
            int c,
            int d,
            int x,
            int s)
        {
        return RL(a + F4(b, c, d) + x + unchecked((int) 0x50a28be6), s);
        }

        internal override void ProcessBlock()
        {
            int a, aa;
            int b, bb;
            int c, cc;
            int d, dd;

            a = aa = H0;
            b = bb = H1;
            c = cc = H2;
            d = dd = H3;

            //
            // Round 1
            //
            a = F1(a, b, c, d, X[ 0], 11);
            d = F1(d, a, b, c, X[ 1], 14);
            c = F1(c, d, a, b, X[ 2], 15);
            b = F1(b, c, d, a, X[ 3], 12);
            a = F1(a, b, c, d, X[ 4],  5);
            d = F1(d, a, b, c, X[ 5],  8);
            c = F1(c, d, a, b, X[ 6],  7);
            b = F1(b, c, d, a, X[ 7],  9);
            a = F1(a, b, c, d, X[ 8], 11);
            d = F1(d, a, b, c, X[ 9], 13);
            c = F1(c, d, a, b, X[10], 14);
            b = F1(b, c, d, a, X[11], 15);
            a = F1(a, b, c, d, X[12],  6);
            d = F1(d, a, b, c, X[13],  7);
            c = F1(c, d, a, b, X[14],  9);
            b = F1(b, c, d, a, X[15],  8);

            //
            // Round 2
            //
            a = F2(a, b, c, d, X[ 7],  7);
            d = F2(d, a, b, c, X[ 4],  6);
            c = F2(c, d, a, b, X[13],  8);
            b = F2(b, c, d, a, X[ 1], 13);
            a = F2(a, b, c, d, X[10], 11);
            d = F2(d, a, b, c, X[ 6],  9);
            c = F2(c, d, a, b, X[15],  7);
            b = F2(b, c, d, a, X[ 3], 15);
            a = F2(a, b, c, d, X[12],  7);
            d = F2(d, a, b, c, X[ 0], 12);
            c = F2(c, d, a, b, X[ 9], 15);
            b = F2(b, c, d, a, X[ 5],  9);
            a = F2(a, b, c, d, X[ 2], 11);
            d = F2(d, a, b, c, X[14],  7);
            c = F2(c, d, a, b, X[11], 13);
            b = F2(b, c, d, a, X[ 8], 12);

            //
            // Round 3
            //
            a = F3(a, b, c, d, X[ 3], 11);
            d = F3(d, a, b, c, X[10], 13);
            c = F3(c, d, a, b, X[14],  6);
            b = F3(b, c, d, a, X[ 4],  7);
            a = F3(a, b, c, d, X[ 9], 14);
            d = F3(d, a, b, c, X[15],  9);
            c = F3(c, d, a, b, X[ 8], 13);
            b = F3(b, c, d, a, X[ 1], 15);
            a = F3(a, b, c, d, X[ 2], 14);
            d = F3(d, a, b, c, X[ 7],  8);
            c = F3(c, d, a, b, X[ 0], 13);
            b = F3(b, c, d, a, X[ 6],  6);
            a = F3(a, b, c, d, X[13],  5);
            d = F3(d, a, b, c, X[11], 12);
            c = F3(c, d, a, b, X[ 5],  7);
            b = F3(b, c, d, a, X[12],  5);

            //
            // Round 4
            //
            a = F4(a, b, c, d, X[ 1], 11);
            d = F4(d, a, b, c, X[ 9], 12);
            c = F4(c, d, a, b, X[11], 14);
            b = F4(b, c, d, a, X[10], 15);
            a = F4(a, b, c, d, X[ 0], 14);
            d = F4(d, a, b, c, X[ 8], 15);
            c = F4(c, d, a, b, X[12],  9);
            b = F4(b, c, d, a, X[ 4],  8);
            a = F4(a, b, c, d, X[13],  9);
            d = F4(d, a, b, c, X[ 3], 14);
            c = F4(c, d, a, b, X[ 7],  5);
            b = F4(b, c, d, a, X[15],  6);
            a = F4(a, b, c, d, X[14],  8);
            d = F4(d, a, b, c, X[ 5],  6);
            c = F4(c, d, a, b, X[ 6],  5);
            b = F4(b, c, d, a, X[ 2], 12);

            //
            // Parallel round 1
            //
            aa = FF4(aa, bb, cc, dd, X[ 5],  8);
            dd = FF4(dd, aa, bb, cc, X[14],  9);
            cc = FF4(cc, dd, aa, bb, X[ 7],  9);
            bb = FF4(bb, cc, dd, aa, X[ 0], 11);
            aa = FF4(aa, bb, cc, dd, X[ 9], 13);
            dd = FF4(dd, aa, bb, cc, X[ 2], 15);
            cc = FF4(cc, dd, aa, bb, X[11], 15);
            bb = FF4(bb, cc, dd, aa, X[ 4],  5);
            aa = FF4(aa, bb, cc, dd, X[13],  7);
            dd = FF4(dd, aa, bb, cc, X[ 6],  7);
            cc = FF4(cc, dd, aa, bb, X[15],  8);
            bb = FF4(bb, cc, dd, aa, X[ 8], 11);
            aa = FF4(aa, bb, cc, dd, X[ 1], 14);
            dd = FF4(dd, aa, bb, cc, X[10], 14);
            cc = FF4(cc, dd, aa, bb, X[ 3], 12);
            bb = FF4(bb, cc, dd, aa, X[12],  6);

            //
            // Parallel round 2
            //
            aa = FF3(aa, bb, cc, dd, X[ 6],  9);
            dd = FF3(dd, aa, bb, cc, X[11], 13);
            cc = FF3(cc, dd, aa, bb, X[ 3], 15);
            bb = FF3(bb, cc, dd, aa, X[ 7],  7);
            aa = FF3(aa, bb, cc, dd, X[ 0], 12);
            dd = FF3(dd, aa, bb, cc, X[13],  8);
            cc = FF3(cc, dd, aa, bb, X[ 5],  9);
            bb = FF3(bb, cc, dd, aa, X[10], 11);
            aa = FF3(aa, bb, cc, dd, X[14],  7);
            dd = FF3(dd, aa, bb, cc, X[15],  7);
            cc = FF3(cc, dd, aa, bb, X[ 8], 12);
            bb = FF3(bb, cc, dd, aa, X[12],  7);
            aa = FF3(aa, bb, cc, dd, X[ 4],  6);
            dd = FF3(dd, aa, bb, cc, X[ 9], 15);
            cc = FF3(cc, dd, aa, bb, X[ 1], 13);
            bb = FF3(bb, cc, dd, aa, X[ 2], 11);

            //
            // Parallel round 3
            //
            aa = FF2(aa, bb, cc, dd, X[15],  9);
            dd = FF2(dd, aa, bb, cc, X[ 5],  7);
            cc = FF2(cc, dd, aa, bb, X[ 1], 15);
            bb = FF2(bb, cc, dd, aa, X[ 3], 11);
            aa = FF2(aa, bb, cc, dd, X[ 7],  8);
            dd = FF2(dd, aa, bb, cc, X[14],  6);
            cc = FF2(cc, dd, aa, bb, X[ 6],  6);
            bb = FF2(bb, cc, dd, aa, X[ 9], 14);
            aa = FF2(aa, bb, cc, dd, X[11], 12);
            dd = FF2(dd, aa, bb, cc, X[ 8], 13);
            cc = FF2(cc, dd, aa, bb, X[12],  5);
            bb = FF2(bb, cc, dd, aa, X[ 2], 14);
            aa = FF2(aa, bb, cc, dd, X[10], 13);
            dd = FF2(dd, aa, bb, cc, X[ 0], 13);
            cc = FF2(cc, dd, aa, bb, X[ 4],  7);
            bb = FF2(bb, cc, dd, aa, X[13],  5);

            //
            // Parallel round 4
            //
            aa = FF1(aa, bb, cc, dd, X[ 8], 15);
            dd = FF1(dd, aa, bb, cc, X[ 6],  5);
            cc = FF1(cc, dd, aa, bb, X[ 4],  8);
            bb = FF1(bb, cc, dd, aa, X[ 1], 11);
            aa = FF1(aa, bb, cc, dd, X[ 3], 14);
            dd = FF1(dd, aa, bb, cc, X[11], 14);
            cc = FF1(cc, dd, aa, bb, X[15],  6);
            bb = FF1(bb, cc, dd, aa, X[ 0], 14);
            aa = FF1(aa, bb, cc, dd, X[ 5],  6);
            dd = FF1(dd, aa, bb, cc, X[12],  9);
            cc = FF1(cc, dd, aa, bb, X[ 2], 12);
            bb = FF1(bb, cc, dd, aa, X[13],  9);
            aa = FF1(aa, bb, cc, dd, X[ 9], 12);
            dd = FF1(dd, aa, bb, cc, X[ 7],  5);
            cc = FF1(cc, dd, aa, bb, X[10], 15);
            bb = FF1(bb, cc, dd, aa, X[14],  8);

            dd += c + H1;               // final result for H0

            //
            // combine the results
            //
            H1 = H2 + d + aa;
            H2 = H3 + a + bb;
            H3 = H0 + b + cc;
            H0 = dd;

            //
            // reset the offset and clean out the word buffer.
            //
            xOff = 0;
            for (int i = 0; i != X.Length; i++)
            {
                X[i] = 0;
            }
        }
    }

}
